An injecting machine for receiving and mixing two different liquids together to inject a predetermined measured amount of a mixture of the two different liquids is known as disclosed in JP-A-2007-76276.
FIG. 8 hereof shows an injecting machine disclosed in JP-A-2007-76276. A first cylinder 101 forces a first liquid 102 out while a second cylinder 103 forces a second liquid 104 out. The first liquid 102 and the second liquid 104 are combined together in a mixer 105 to flow into a mixing cylinder 106. The first and second liquids 102, 104 are sufficiently mixed together by rotation of a mixing shaft 107 in the mixing cylinder 106 to provide a liquid mixture of the first and second liquids 102, 104. The liquid mixture is introduced through a connecting passage into an injection cylinder 109.
Referring to FIG. 9A, the liquid mixture indicated at 111 collects in a forward space formed forwardly of a plunger 112. The forward space becomes large as the plunger 112 moves back, thereby increasing an amount of the collecting liquid mixture. As shown in FIG. 9B, a sufficient amount of the liquid mixture collects in the forward space immediately before injection of the liquid mixture when the plunger 112 is in a sufficiently retracted position.
The liquid mixture 111 collects in the forward space as follows. A first part 111a of the mixture first enters the forward space and then moves back with the plunger 112 such that the succeeding part of the mixture enters the forward space, and a last part 111b of the mixture finally enters and remains in the forward space furthest from the plunger 112.
As the plunger 112 advances, the mixture is injected in a “first-in last-out” manner in which the last part 111b which finally entered the forward space is first injected and the first part 111a which first entered the forward space is finally injected.
The liquid material tends to change its quality as time elapses. The first part 111a remains in the forward space for a long time while the last part 111b remains in the forward space for a short time. Since the first part 111a and the last part 111b remain in the forward space for different periods of time, as a result, undesirable difference in quality between the first part 111a and the last part 111b occurs. As measures against this undesirable quality difference, it is necessary for an injecting machine to inject a liquid mixture in a “first-in first-out” manner.
An object of the present invention is to provide an injecting machine for two different liquids, the machine being configured to inject a mixture of the two different liquids in a first-in first-out manner.